Investigation of High-Pressure and Temperature Behavior of Surfactant-Containing Periodic Mesostructured Silicas

Surfactant-containing periodic mesostructured silica materials, namely SBA-16 and FDU-12, were studied under pressures between 1 and 4 GPa and temperatures between 100 and 400 degrees C. At 4 GPa crystallization of coesite can be achieved already at 200 degrees C. The mild transition of amorphous to crystalline silica is believed to be accomplished by the inbuilt hydroxyl groups present in the starting material. At 2 GPa the crystallization of quartz is accomplished at a temperature of 400 degrees C. Both quartz and coesite are obtained in nanocrystalline form.